This invention relates to a magnetic card sensor, especially to a arranged to sense the thickness of a card.
Magnetic cards are specified in ISO Standards Nos. 7810 and 7811, which sets out the card dimensions including the thickness, which is 0.76mm, and the position of the data bearing magnetic stripe. All credit/debit and bank cards conform to this standard worldwide. The cards are usually made of plastics material which at a thickness of 0.76mm gives a semi-rigid card. Such a card will be referred to in this specification as a standard card.
Self service terminals, such as automated teller machines (ATMs), which are operated by insertion of a standard card are often provided with a shutter mechanism within the card entry slot to protect the interior of the terminal from the environment and from vandals. The terminals are then provided with a card sensor which senses insertion of a card into the slot, and passes a signal to a processor operating the terminal. The shutter is then opened, and a transport system draws the card into the terminal to be positioned adjacent to a card reader/writer. It is a requirement that such a transport system operates very smoothly so that the card is moved smoothly and accurately over the head of the card reader/writer.
Such card sensors operate by sensing the presence of the magnetic stripe on the card when the card is in the slot in the specified position.
Another type of card which has come into wide use is a card, often of paper but sometimes of plastics material, used for telephone cards or public transport tickets. Such cards are often of similar size to the standard cards, and often have a magnetic stripe in the same position as a standard card, but they are thinner, and flexible. In this specification, such a card will be referred to as a thin card.
Sometimes thin cards are inserted by error, or mischief or malice, into the card slot of a self service terminal designed to operate with a standard card. Since currently-available card sensors operate by sensing the magnetic stripe on the card, the shutter is opened and the transport system draws the thin card into the terminal. Since the transport system is designed to operate on the greater thickness of a standard card, a thin card cannot be gripped, with the result that it can neither be ejected from the terminal nor moved into a purge bin. The terminal is therefore in effect jammed by the thin card and is put out of service until a service engineer can visit its site to clear the jam. This is inconvenient and expensive for the financial organization operating the terminal.